Hi all,
Since this was my research field before teaching this is exciting to me.
Since accessing the NY Times takes a registration, I decided to copy it
and paste it here. I suggest going to the CERN site that Jack Uretsky
mentioned to see cool pictures and get links to science info and
explanations. It is exciting but there is still mumbling in the
communities about it, since the Europeans wanted to bet the Americans to
the discovery. Enjoy.
Sam Held
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February 10, 2000 - New York Times
Particle Physicists Getting Closer to the Bang That Started It All
By JAMES GLANZ
Scientists in Geneva have re-created a primordial form of matter that
physicists believe last existed in abundance when the universe was an
exploding fireball only a fraction of a second old.
The new material is a highly compressed gas of the particles called
quarks
and gluons, the building blocks of ordinary particles like the protons
and
neutrons within all the atoms in the universe today. In scientific
importance, the long-sought achievement might be compared to the first
splitting of the atom to reveal its individual parts.
The achievement will be announced today at CERN, the European particle
physics laboratory where the work was carried out. The finding moves
experimental physics closer than it has ever been to the presumed moment
at which the universe came into being and could help cosmologists better
understand the driving forces behind the primordial explosion itself.
The
matter's existence confirms one of the most abstruse of all predictions
by
theoretical particle physicists.
Quarks, and the gluons that powerfully bind them, are normally joined to
form protons and neutrons and cannot be shaken loose individually no
matter how hard pairs of the ordinary particles are smashed together. To
create the new material, the scientists have, in effect, compressed and
heated a ball of protons and neutrons so that they melted into their
constituent quarks and gluons, which then floated freely in a laboratory
for the first time.
The compression was achieved by smashing together entire lead nuclei
containing hundreds of protons and neutrons each, rather than mere pairs
of them.
"It does indicate that a new state of matter is created," said Dr.
Johanna
Stachel, a physicist at the University of Heidelberg in Germany who is
the
spokeswoman for one of the multinational collaborations that operates a
large particle detector, called NA45, at the Geneva laboratory. "This
new
state we think the universe was in until about 10 microseconds after the
Big Bang, and then crystallized into the particles as we know them now."
The Big Bang is the colossal explosion in which most cosmologists
believe
the universe was born, some 15 billion years ago. A microsecond is a
millionth of a second.
The laboratory's experiment, said Dr. Michael Turner, a cosmologist at
the
University of Chicago, "helps take us back to when the universe was a
soup
of the most fundamental particles we know."
Because of the tight connection to cosmology, said Dr. Edward Shuryak, a
physicist at the State University of New York in Stony Brook, the Geneva
laboratory's achievement is being called the "Little Bang."
Known more technically as "quark-gluon matter," the material is also a
boon for theoretical physicists, since their theory of strong particle
interactions, called quantum chromodynamics, had predicted that the
bizarre state should exist.
Physicists know of six different types of quarks, which go by the
somewhat
whimsical designations up, down, charm, strange, top and bottom. Pairs
and
threesomes of quarks bind together to make up ordinary particles of
matter. Protons, for example, consist primarily of two up quarks and one
down quark, while the less common particles called kaons consist of a
strange quark and either an up or a down.
Oddly, the strength with which gluons bind quarks turns out to be weak
when the quarks are close together and grows powerful when they are
distant from each other, as if they were connected by elastic.
But Dr. Shuryak and others came to the conclusion that quarks could roam
free if enough protons and neutrons could be heated to a temperature
about
100,000 times higher than the center of the sun and compressed to a
density roughly 10 times that of an ordinary atomic nucleus. Small
clouds
of quarks effectively screen one another from the gluon force of more
distant quarks, cutting the elastic connections.
The equations of quantum chromodynamics are so complex that the
theoretical properties of quark-gluon matter can be explored only on the
world's largest computers.
To test whether this state of matter can exist in reality, the
scientists
in Geneva used their Super Proton Synchrotron to accelerate lead nuclei
to
an energy of 33 trillion electron volts. Traveling at nearly the speed
of
light, those nuclei were smashed into a lead foil, producing hot, dense
matter in the collisions.
After a fleeting existence, the quark-gluon matter should then cool and
condense into ordinary matter and explode in a hail of thousands of
ordinary particles. Seven different particle detectors examined the
residue of millions of lead collisions for evidence that the quark-gluon
matter had been created.
"It is sort of a criminal court procedure, where you have proof by
circumstantial evidence," said Dr. Reinhard Stock, a physicist at the
University of Frankfurt who is the spokesman for a collaboration
centered
on a detector called NA49.
The fingerprints of the deed are clear, said Dr. Stock. They include
detection of many more particles that contain strange quarks than an
ordinary smash-up would produce, and fewer particles containing charm
quarks -- the indications seen by the Geneva lab's detectors.
"We have opened the door," said Dr. Claude Ditraz, the laboratory's
director of research, calling the new results "compelling evidence that
we
have created a new state of matter in which quarks are 'deconfined.' "
Cosmologists believe that much of the character of the universe, and
perhaps the fury of the Big Bang explosion itself, was determined by a
series of so-called phase transitions like the coalescence of ordinary
matter from the quark-gluon plasma.
"This is really a concrete illustration of how cosmologists can benefit
from accelerators, which can recreate the conditions that existed during
the earliest moments of the universe," said Dr. Turner of the University
of Chicago.
Though quark-gluon matter is rare, physicists theorize that small
amounts
of it may be generated when energetic particles from space called cosmic
rays crash into planetary bodies like Earth.
The announcement sets the stage for much more powerful experiments,
expected to begin this spring, using the Relativistic Heavy Ion Collider
at the federal Brookhaven National Laboratory in Upton, N.Y.
Those experiments will initially collide gold nuclei with 10 times
higher
energy than CERN has mustered, said Dr. Thomas Ludlam, a physicist who
is
an administrator of the program at Brookhaven. The experiments should
produce an even more exotic entity called a quark-gluon plasma and allow
for much more intensive study of the substances.
"It's as if you're trying to discover steam and you can make a few
little
puffs of steam," he added. "But with a better pressure cooker you have
enough time to stick a thermometer in and discover the thermodynamic
properties of steam."